Moreover, cyclization was observed to increase assay sensitivity, as the cyclic EBNA-2 and pro-filaggrin peptides had higher sensitivitities compared to the linear peptides (p = 0.0331), 67% and 44% of the RA sera reacted to the cyclic and linear EBNA-2 peptide, respectively, whereas 68% and 44% of the RA sera reacted to the cyclic and linear pro-filaggrin peptides, respectively. This evidence concerns the gene FLG and rheumatoid arthritis.